In recent years, in accordance with development of the technology on database retrieval, it has become possible to efficiently retrieve required information by entering conditions for retrieving. Under the circumstances as described above, there has been proposed a technology for retrieving, and extracting a desired phrase from an enormous amount of phrases, using the conditions for retrieving set by a user based on the phrase which the user desires to retrieve.
There are some examples of publications disclosing the above technology such as Japanese Patent Laid-Open Publication No. HEI 2-115974 with the title of "Language retrieval device", Japanese Patent Laid-Open Publication No. HEI 3-5883 with the title of "Word processing supporting device", and Japanese Patent Laid-Open Publication No. HEI 6-348691 with the title of "Word selecting method in a word processing device".
In the language retrieval device disclosed in Japanese Patent Laid-Open Publication No. HEI 2-115974, when the user wants to know a Japanese phrase having a certain meaning, he enters the meaning and any phrase having a corresponding notation from a dictionary in Japanese language according to the notation corresponding to the entered meaning is retrieved.
The word processing supporting device disclosed in Japanese Patent Laid-Open Publication No. HEI 3-5883 automatically executes extraction of key words and creation of retrieval expressions (for instance, Retrieval expression 1: "having a meal", Retrieval expression 2: "slim and long", and Retrieval expression 3: "substance") from a question made in natural language entered by the user (Example: "a pair of slim and long substances used when Japanese people have a meal"), and provides a desired noun ("a pair of chop sticks" in this example) by searching the dictionary.
In the word selecting method in a word processing device disclosed in Japanese Patent Laid-Open Publication No. HEI 6-348691, any phrase having the same concept as that of one or more words entered by the user is extracted and displayed based on a dictionary previously provided therein, and then the processing for further extracting and displaying some phrases having the same concept as those specified by the user from the displayed phrases is repeated so that a desired phrase can be specified.
Although it is possible to retrieve and extract a desired phrase from an enormous amount of phrases using conditions for retrieving in the conventional technology as described above, a result thereof is sometimes completely unexpected because the retrieval conditions as a reference for retrieval and selection are specified depending on the user's subjective concept of the desired phrase without entering any objective reference for retrieving.
In other words, it is necessary to set conditions for retrieving accurately expressing the concept in order to obtain a result the user desires, and, if retrieval and selection are performed with a condition for retrieving expressing a wide concept, a result of the retrieval satisfies the conditions for retrieving set by the user, but it is not a result of complete and strict retrieval, and even if a user sets a plurality of conditions for retrieving to obtain a result of retrieval based on strict conditions, when the plurality of conditions for retrieving express concepts contradictory to each other, it is impossible to obtain a result of retrieval, or the obtained result is far different from that which the user wants to obtain.